Carburetor with choke control



Dec. 7, 1937.

' A R. BAKER I 2,101,039

CARBURETOR WITH CHOKE CONTROL Original Filed March 20, 1953 2 sheets sheet 2 Patented Dec. 7, 1937 UNITED STATES VATENT OFFICE CARBURETOR WITH CHOKE CONTROL Application March 20, 1933, Serial No. 661,809 Renewed July 29, 1935 6 Claims.

This invention relates to carburetors and is an improvement on the carburetor shown in my Patent No. 1,877,117, granted September 13, 1932.

An object of the invention is to provide a car- 5 buretor adapted for use with low grade blended fuel such for example as a gasoline having a high end point which under normal conditions is unsatisfactory for use in engines having a high compression ratio and further to provide a carburetor which will reduce excessive detonation when operating with low grade fuel.

A further object is to provide a carburetor having a combination of automatic choke and accelerating valve which valve is operated in response to varying load demands upon the engine.

A further general object is to simplify the construction and to increase the efficiency of carburetors in general and more particularly carburetors such as that shown in the patent referred to.

Referring to the accompanying drawings, which are made a part hereof and on which similar reference characters indicate similar parts,

Figure 1 is a plan view of the carburetor with a portion in section to show a motor fuel jet,

Figure 2, a section on line 2-2 of Figure 1,

Figure 3, a section on line 3-3 of Figure 1,

Figure 4, a detail showing mechanism for operating the throttle valve,

Figure 5, a sectional view of a modified form of fuel jet,

Figure 6, a view on line downward as indicated by the arrows,

Figure 7, a view on line 'l-'! of Figure 2 looking upward as indicated by the arrows,

Figure 8, a section on line 8-8 of Figure 6,

Figure 9, a section on line 9-9 of Figure 6, and

Figure 10, a section on line I9-l9 of Figure 6.

In the drawings, casing elements Ill and H are removably secured together in any suitable way. A fuel well I2 is formed in the lower casing element i and motor fuel overflows into the well 12 from a fuel pan 9. Fuel is delivered into the pan through a port 13 to which is connected a fuel conduit from the tank which may be located at some remote place on the vehicle. Flow of fuel into the pan 9 is controlled by a float M which is pivotally attached at [5 to a screw i6 which is threaded through the casing I I. A portion I8 of the upper casing encloses a chamber 11 which forms an intake chamber through which the fuel passes into the engine. The casing I8 is flanged at l9 which flange is drilled at 20 to receive bolts, not shown, by means of which the 6-6 of Figure 2 lookin (Cl. 261-64) 2 a carburetor may be attached to the side of the engine. An expansion chamber 2| is formed in the upper casing H and forms what may be regarded as a chamber continuous with the well l2. In order to secure the best operating results the carburetor should be mounted on the engine with the side of the carburetor which contains the well l2 preferably positioned toward the front of the vehicle. With the well 12 so positioned the float M will have a tendency to remain lower and thus to open the inlet port 13 to permit a more free flow of fuel into the well. The purpose of this arrangement is that when the car is climbing a hill and is in an inclined position, the float will be at a lower level and this will insure a full flow of gasoline into the pan. This is as it should be; for in climbing a hill the engine makes greater demands for fuel than when on the level, or when descending a hill and it is necessary therefore to provide for this free flow of fuel. When descending a hill the car is tilted into the other direction. There is less demand for a rich fuel at this time and since the float rises it retards the flow of fuel into the pan and thus insures a leaner mixture at a time when a lean mixture is sufficient for operating the engine. Positioning of the carburetor therefore, as indicated, enables an operator to economize on fuel.

A tube or pipe 22 is positioned in the well l2 extending to a point near the bottom of the well. The upper end of this tube connects with a chamber 23 with which chamber an annular passage 24 connects. This annular passage is between a needle valve stem 25 and a tube '5 having an enlarged end which is threaded into a bore in the carburetor casing. The valve stem 25 has a tapered end 26 which controls a valve 21 through which motor fuel is sprayed into a hot cap 34 positioned in the exhaust manifold 35. An air intake pipe 28, having a ball check valve 90, is secured in the casing I i and extends down into a tube 29. This tube has ports Slat its lower end which communicate with a body of liquid fluid in the well I2. A cup 32 is fitted in the lower end of the tube 29 and into this cup extends the lower end of the tube 28. The'tube 28 is slotted at 30 as shown and this slot extends up above the normal level of the fuel in the pan 9. A tube 33 is fitted within the tube 29 and spaced from the sides of the tube 28. Air is sucked down through the tube 28 and passes out the end of this tube and up around the outside of the tube and the inside of the cup and on up into the space between the tube 28 and the tube 33. The rising air acts to lift fuel which enters through the ports 3| and carries it up into the pan 9i. The air therefore acts as a pump to lift the fuel into the pan. During this course, the air takes up an appreciable amount of lighter fuel elements so that when the air leaves the space 2i above the fuel it is partial ly ladened with vaporized fuel. The liquid drops of the fuel, however, which may have been carried up with the rising stream of air, fall back into the Well l2. There will be something of a churning up of the fuel in the pumping operation just described which will assist the air in taking on a partial load of vaporized fuel elements.

A port 8 communicates with the space 2| through which the fuel ladened air passes to a space 6 between the tube 5 and the tube 7. The tube 7 is threaded into the carburetor casing. The hot cap 34 also has an enlarged inner end which is screw threaded into the same bore of the casing. Air drawn through the annular space 6 passes out around the end of the tube 5 and acts to draw fuel through the space 24. The fuel and air are mixed in the hot cap 34 and. also are here heated by the hot gases passing out through the exhaust manifold 35. A valve stem 25 is screw threaded at 35 into a screw cap 31. The screw cap 3'! is threaded into a cap 33 at 39. The threads 36 and 39 have a difierentpitch so the rotation of the screw cap 3? will move the valve stem 25 endwise. Instead of having the threads of a different pitch of course it would be possible to have one set of threads right hand and the other left hand to effect the adjustment. The valve stem also carries a disk 49 to which is secured one end of a flexible diaphragm or bellows 4i which acts to seal the chamber 23 to prevent leakage of fuel elements out past the screw threads 39 and 36. The sleeve 1 is surrounded by a spiral 42 through which the fuel mixture from the hot cap 34 travels to a port 43 through which it passes to an axial bore 44 and out through radial bores 45 and a space 46 from which it passes into the chamber 11. A sleeve 58 in conjunction with a conical surface 49 on the end of a cap 48 forms a Venturi opening 4'! through which air passes into the chamber l7. The velocity of the air through the Venturi opening 41 is suificiently high to suck fuel gases through the opening 45 and to thoroughly mix all elements of the fuel charge as they enter into the intake chamber ll. Any liquid fuel elements which may condense about the casing into which the element 4-8 is threaded may drip back through a port 5| where they are sucked up and vaporized by the stream of vaporized fuel passing out through the radial bores 45. The Venturi sleeve 56 has a pin 52 which carries a roller 53. This roller operates in a slot 5'! in the casing i0 and in an arcuate slot in an operating cam arm 54. The cam arm 54 is pivotally supported on the carburetor casing on an eccentric 55 which is operated by a lever 56. Movement of the lever 56 by virtue of the eccentric 55 will adjust the arm 54 vertically. This adjusts the Venturi sleeve as a Whole to vary the opening at 41 to determine the idling opening of the Venturi. The cam arm 54 is operated by means of a lever 85 which is attached thereto at 58. When the link 86 is pushed toward the right the cam arm 54 will swing in a counterclockwise direction on its eccentric support and the curved slot in the cam arm 54 will move the roller 53 vertically carrying the Venturi sleeve 59 upwardly. The first movement of the cam arm 54 will impart a rapid upward movement to the sleeve. The. movement of the sleeve relative to movement of the cam arm 54 will decrease as the sleeve approaches its uppermost position, When aioipa the arm 54 has reached the dotted line position shown in Figure 4 movement of the link 85 will cause a very slight movement of the Venturi sleeve. When returning from the closed position the open movement will first be very slow and then will gradually increase as the cam arm approaches the position shown in full lines in Figure 4. The cap 48 may also be given a slight vertical adjustment after it has been screwed to position. This adjustment is made by means of a key member 86 having a ball 8| through which extends a pin 82. The pin engages a slot 83 in the upper end of the cap. The key member is provided with a packing ring to prevent leakage of fuel elements out past the wallsof the tube enclosing it. The upper end of the opening is closed by a screw cap 84. When it is desired to adjust the cap '48 the cap 84 is removed and the key member 80 rotated by ascrew driver or similar toolto rotate the cap member 48, the pawl and slot connection 8!, 82 and 83 serving as a universal joint. A tube 59 extends through the walls of the air inlet 92. This tube communicates with atmosphere through a port 69. A port Bl forms communication between the fuel pan 9 and the interior of the tube 59. This port is normally closed by a valve 62 which is held against the valve seat by means of a spring 63. A flange portion 64 extends into the path of the lower edge of the Venturi sleeve 53 when this sleeve is depressed. When the lower end of the sleeve engages the disk li i further downward movement of the Venturi sleeve will depress the valve 62. This permits fuel to pass through the port 6! into the tube 59 where it is mixed with air drawn in through the port 60. The fuel charge is delivered into the inlet air stream of the engine. The upper end of the valve 62 is tapered as shown at 9! so that the amount of fuel delivered through the port 6| increases as the valve is further depressed.

The structure just described operates to supply the additional fuel necessary as the throttle is opened beyond a predetermined extent.

Among the features of the present carburetor are the means for maintaining the fuel charge with the correct proportions of fuel and air. Insofar as possible these correct proportions are automatically maintained in response to the demands of the engine under increased load, increased speed, or accelerating conditions. Means about to be described provide automatic control of the fuel charge to meet these conditions. The usual butterfly valve 66 is mounted on a shaft 51 in the intake barrel 92 through which air is delivered to the engine. The shaft 67 is oil center of the butterfly valve as shown best in Figure 9. The shaft 67 has secured thereon an arm carrying a pin 68 which engages the side of a slotted arm 69 which is loosely mounted on the shaft 61., A spring 19 on the shaft 67 tends to urge the shaft 57 in a direction to keep the pin 68in engagement with the lower side of thearm 69. A plunger 10 is pivoted to the slotted end of the arm 69 and this plunger has an enlarged end ll against which seats one end of a spring 12 which surrounds the plunger. The other end of this spring engages a stop 13 positioned within a sleeve 74 and secured therein in any suitable way not shown. A spring 15 surrounds the sleeve l4 and bears against a flange portion 16. A packing cup 80 is secured to the flange portion 76 to provide a seal to prevent leakage between the flange and the walls of an enclosing cylinder 11. A tiny air port 18 communicates with a chamber back of the packmg mp 80. Normally the butterfly valve 66 is in the position shown in Figure 9. This is also the position during idling of the engine. When the engine is first started or when it is accelerated from the idling position there is a strong suction through the tube 92. The first efiect of this suction is to draw in an additional supply of fuel through the tube 59 toenrich the fuel charge. This enrichment will occur before the butterfly valve 69 is materially moved from the position shown in Figure 9. Suction, however, through the tube 92 will swing the butterfly valve 66 in a clockwise direction against the tension of spring 12. But for the vacuum at the back of the cup 80 the sleeve 14 will also be moved to the right. This movement, however, cannot occur quickly due to the vacuum. A strong suction would be necessary to maintain the butterfly valve in an open position but for the fact that as soon as it moves to this position, the sleeve 14 tends to move, the flanged end 16 be ing limited in its movement by the rate with which air may be drawn in through the port 18. As soon as the sleeve '54 has moved to its extreme limit to the right the tension on spring 12 is released so that the valve 69 will remain in its open position and may be maintained in this position by suction which is only suflicient to compress the spring 15. The tension of spring 72 will be so determined as to give the proper fuel mixture at the starting and at the accelerating speed and the spring may be made only with sufficient tension to restore the suction cup to its extreme left position when the throttle has been closed or the engine stopped.

In case of engine back-fire the butterfly valve may yield and swing counterclockwise, the spring 19 restoring it to closed position after the backfire. The butterfiy valve by yielding as indicated prevents any injury as a result of the back-fire.

In the modified form of spray nozzle shown in Figure 5 the valve 81 is made to side Within the bore 88 in a Venturi sleeve 89. This has a neat fit within the Venturi sleeve so as to completely out off the supply of fuel and may be so adjusted as to regulate the supply within any predetermined limits.

In operation air which is partly saturated with lighter fuel is drawn through the port 8 and through the annular spaces surrounding the tube 5. This suction at the end of the tube creates a strong suction through the chamber 23, and thus sucks a charge of motor fuel up through the tube 22. The air which is already partially saturated with motor fuel is mixed with a relatively large volume of atomized motor fuel in the hot cap 34. At this point of mixing the mixture is heated to a relatively high temperature by the exhaust gases passing through the exhaust manifold 35. In the process of heating this mixture of gases to a high temperature some non-condensible gases are formed. Tests have shown that among these gases are carbon monoxide and hydrogen which gases play an important role in subsequent reactions in the engine. The mixture of gases in the cap 34 is too rich to fire. This rich mixture is passed through the spiral passage around the side of the hot cap and passes through bore 43 into bore 44 out through ports 45 and passage 46 into the chamber I 1. This rich mixture of gases is mixed with a relatively large volume of cold air which comes in through the Venturi sleeve 92 and which strikes the sloping portions 49 and is deflected radially outwardly against the walls of the Venturi, creating a strong aspirating action on the rich mixture issuing through the passage 48. The volume of air admitted to the mixture is controlled, of course, by the operator by means of the link 86 which is manually operated. When the Venturi throttle is opened to a predetermined extent it is necessary to supply an additional quantity of motor fuel. This is eiiected by means of the valve 62. As the Ven turi throttle engages the disk 94 it depresses this disk as the throttle is further opened. This permits the raw motor fuel to flow from the re ceptacle 9 into the tube 59 where is passes into the Venturi opening along with air which is drawn in through the port 60.

It will be obvious to those skilled in the art that various changes may be made in my device without departing from the spirit of the invention and therefore I donot limit myself to what is shown in the drawings and. described in the specification, but only as indicated by the appended claims.

Having thus fully described my said inven tion, what I claim as new and desire to secure by Letters Patent, is:-

1. In a carburetor having a butterfly valve, means for operating said valve in response to load demands of the engine comprising means for creating a suction on the butterfly valve so as to open said valve slightly after starting of the engine, and means for maintaining said butterfly valve in an open position solong as the engine is operated at normal speed and under a normal load and means for minimizing the amount of suction required to maintain the valve in open position at operating load after the engine has come up to full operating speed, substantially as set forth.

2. The combination with the air intake to a carburetor, of a butterfly valve, said valve being pivotally mounted off center, resilient means for holding said valve to close off said air intake, means yielding under suction to permit said butterfly valve to open to permit air to flow to the said carburetor, and means for relieving said tension on said butterfly valve whereby the valve may be maintained in an open position with relatively light suction through the said air intake to maintain a proper proportion of air and fuel during normal operation of the engine, substantially as set forth.

3. In a carburetor of the kind described, a Venturi throttle valve, means for operating said Venturi throttle valve comprising a cam element, a pivotal support for said cam element, means for adjusting said support vertically to adjust the idling opening of the throttle, a cam slot, a lug on said Venturi engageable in said slot, means for pivotally swinging said cam to raise and lower the said Venturi throttle, first movement of said cam from open position toward closed position causing relatively rapid movement of the Venturi,

said rapid movement gradually decreasing to a very slow movement as the throttle approaches a closed position, substantially as set forth.

4. In a carburetor having an inlet for air and an inlet for fuel, means for mixing said air and fuel and thereafter adding a large volume of air thereto comprising a Venturi forming sleeve, means for adjusting the air supplying ports comprising an adjustable cap, a threaded stem on said cap, and means engageable with said stem for rotating it to adjust the said cap relative to said sleeve, substantially as set forth.

5. In a carburetor having an air controlling valve means for'operating said valveinresponse toiloadidemands of the engine comprising means for creating asuction on said valveso as to open it a. little. after starting of the engine, means for maintaining; saidvalvein open position so long as the engine-is'operated at normal speed and under normal load, andmeans for minimizing the-amount of suction required to maintain the valve in-open position at operating load after the engine has-.come. up to full-operating speed.

6; The combination with the air intake to a carburetor, of an air-controlling valve, a pair of springs-for holding said valve in closed position, and yielding under suction to permit said. valve toopen to permit air to flow to the said-carburetor andmeans for relieving the tensionof'one of said springs to reduce the pressure tending to closesaid-valvewhereby the'valve may be maintained in-op'en'position with light suction through the air intake-to maintain a proper proportion of air and: fuel during normal operation of the engine;

ARTHUR R; BAKER. 

